A lockset conventionally includes a latch assembly which has a cylindrical bolt supporting body insertable into a cylindrical bore drilled into the edge of the door. Replacement locksets may include a latch assembly which has a larger cylindrical bolt supporting body which is too big to be inserted into the original cylindrical hole. It may also be desirable to enlarge the strike hole in the door jamb. Enlarging a hole is a very difficult proposition.
It is known from U.S. Pat. No. 5,366,326, to snugly fit a hole saw guide into a through hole to be enlarged. This guide has a concentric hole which serves as a bearing surface for the pilot drill of a hole saw as the hole saw is brought into cooperation with the guide to enlarge the hole. The guide is tapered so that this snug fit can be achieved with small variations in hole size.
It is accordingly an object of the present invention to provide a tool for enlarging an existing hole which does not require the securement of a guide within the hole prior to the use of the drilling tool.